It is well known that various yarn processing steps, such as dyeing, steaming, washing, etc., applied to individual yarn strands passing through a continuous process machine cause the yarn to undergo changes, such as shrinkage, which are quite non-uniform. Because of the range of degrees of shrinkage and the difficulties of maintaining and controlling feeding tensions in a large number of yarns, there have been problems associated with excessive tension, causing reduced bulk and, in extreme cases, breakage; and also with excessive slack, permitting portions of the yarn to wind around processing rollers. These problems can exist in the same machine at the same time.
It is also desirable in some processing steps, such as "space dyeing", to be able to maintain a plurality of yarn strands (e.g., 20 to 80 strands at a time) in a predetermined relative relationship, rather than handling them completely independently or as a loosely organized bundle.
One solution which has been employed to overcome these and other problems is to form the warp yarns into a "temporary" fabric, i.e., a structure which is a fabric in the sense of having the structural characteristics of a fabric but which is not intended to stay in that form as a final product. One such "temporary" fabric is knitted material wherein the yarn is passed through a knitting machine and knitted into, e.g., a tubular form. The knitted tube is then dyed, steamed or otherwise processed, after which the tube is unraveled and the resulting yarn, which may have an intentional crimp therein, is available for incorporation in a true "end product". This is commonly referred to as "knit-deknit".
A similar solution is "weave-deweave" wherein weft or "filler" threads or yarns are woven into the warp yarns to be processed, usually forming a rather loosely woven "temporary" fabric. After processing, the filler is removed, leaving the treated warps available for production.
Yet another solution is to false-twist portions of yarns around portions of adjacent yarns, thereby forming a tubular structure resembling a tube of netting or chicken wire fencing (although not made of wire) which, after processing, is disassembled.
Examples of these processes can be found in the following U.S. Pat. Nos.:
3,012,303 Whitaker, et al
3,102,322 Whitaker
3,120,733 Breen
3,343,242 DeWitte
3,456,431 Fleissner
3,602,968 Adolff
3,605,225 Gibson, et al
3,908,247 Murphy
3,997,950 Gibson
While these prior art solutions are apparently usable, it is necessary to form these temporary fabrics in a separate manufacturing step with the concurrent costs for rather complex equipment and labor. In the weave-deweave processes, the weft or filler itself represents considerable expense, not only in its purchase and use, but also in that the weft removal step is often the main limitation on the speed with which the web or tape can be dewoven and the yarn rewound.